Directing fuel through an injection into a central portion of a combustion chamber in a spark ignited internal combustion engine is known as per example, in U.S. Pat. No. 5,335,635 to Kadoi and 5,529,038 to Tsuchida. Both of these patents inject fuel into a central region of the combustion chamber. Also, the ignition of fuel by a spark plug located radially outward from the central injection is disclosed in the '038 patent. While an engine will operate successfully with such an arrangement, the emissions of hydrocarbons has been greater than allowed under current standards and requirements.
Hydrocarbon emissions can be reduced by preheating the fuel prior to ignition by a spark plug. The present invention provides a separate intake path for hot exhaust gas recirculation products to direct this hot medium to the central region of the combustion chamber. At an appropriate time in the engine cycle, the centrally located direct fuel injector sprays fuel through the hot medium which results in heating and evaporation of the fuel. The preheated fuel moves radially outward in the combustion chamber to mix with air flowing through a second inlet and together the heated mixture is ignited by a radially outwardly located spark plug.
Other features, objects, and advantages of the invention will become more apparent as the following description proceeds, especially when considered with the accompanying drawings and claims.